This study was carried out to determine physiological and biochemical changes in C. moschata inoculated with a Nigerian strain of MWMV isolated from Lagenaria breviflora in Calabar, Nigeria. The virus infection resulted in significant (p#0.05) reductions in plant height, leaf area and number of leaves produces with highest percentage difference of 39.3% (42 PID), 60.9% (35 PID) and 25.7% (49 PID), respectively. There was a significant (p#0.05) difference in chlorophyll content between inoculated and healthy plants. The chlorophyll content of inoculated plants at all stages of growth was lower compared with the healthy plants. Chlorophyll b content was higher than Chl a in both inoculated and healthy plants. Chlorophyll a, b and total Chlorophyll were significantly reduced in inoculated plants when compared with the healthy ones. Of the twelve photochemicals screened, alkaloids, glycosides, saponins, tannins, terpenoids, steroids, polyphenols and reducing sugars were present while phlobatanins, anthraquinones and hydroxymethyl anthraquinones were absent. Moroccan watermelon mosaic virus engendered reductions in alkaloids (32.1%), reducing sugars (42.0%), saponins (33.6%), terpenoids (25.0%) and steroids (15.0%) and increase in inoculated samples of glycosides (14.8%) and flavonoids (12.5%). Effect of MWMV on proximate compositions of C. moschata revealed significant p#0.05) reductions in lipid (25.0%) and ash (14.6%) and significant (p$0.05) increases in protein (23.4%) and fibre (10.5%). Effect of the virus on carotene, vitamin A and C were insignificant. Infection of MWMV also led to significant decreases in the contents of K (48%), Fe (28.6%), Zn (25.0%) and Mg (22.0%), while Cu recorded 100% increase in inoculated samples. Marginal increase in Ca and P were recorded in inoculated samples. Infection of MWMV on antioxidants caused significant increase in inoculated samples of hydrocyanic acid and insignificant increases in total and soluble oxalate and phytic acid. Increases recorded in the antioxidant contents in plants inoculated with MWMV resulted in reduced bioavailability of minerals in the vegetable. Reduction in chlorophyll contents in inoculated plants would be a major factor explaining poor growth of host plants with attendant reductions in mineral elements of C. moschata. Changes in physiological and biochemical parameters induced by MWMV altered vital metabolic processes of C. moschata.