Aim: To investigate the prevalence of malaria and how demographic factors influence malaria parasite transmission among persons attending primary health care facilities in Oyigbo LGA, Rivers State, South-South, Nigeria. Methodology: Intra-venous blood samples were obtained from 190 participants who enrolled for the study. These blood samples were stored in ethylene diamine tetra acetate bottles (EDTA) and used to make thick and thin films for malaria parasite detection using standard parasitological techniques (Cheesbrough 1998). Questionnaires were administered to the participants to obtain their demographic data. Data were analysed using the Statistical Package for Social Sciences version 25 and presented using descriptive statistics. Chi-square was used to obtain level of significance (p<0.05). Results: Of the 190 persons examined, 109 were positive, giving a prevalence of 57.4%. Plasmodium falciparum was the only malaria parasite observed. Females 67 (59.82%) were more affected than males 42 (53.84%) but this difference was not statistically significant (p>0.05). Age group 41-50 and those with Secondary education had higher prevalence. The difference observed in these groups was statistically significant (p<0.05). Artisans had the highest prevalence whereas the unemployed had the least prevalence. However, this difference was not statistically significant (p>0.05). Conclusion: Demographic factors have been shown to influence malaria transmission. Therefore, malaria control efforts should be intensified, taking into cognizance, the role of demographic factors in transmission.