Assessment of genotypic and phenotypic diversity of the rain-fed Sorghum in the sahelian zone of Cameroon. Objectives: This study was conducted to determine the genotypic and phenotypic diversity in the accession of the rain-fed Sorghum in the sahelian zone of Cameroon and to estimate the genetic parameters, which can be used to create new varieties of Sorghum in Cameroon. Methodology and results: Forty-four (44) accessions were grown in a randomized complete bloc design with three replications. The results showed there was a large morphological diversity among the Sorghum accessions. Furthermore, these diversities were organized around vegetative and yield characters, which divided the accessions into three groups. The individual in group three (3) showed interesting performance in term of plant height and grain yield parameters. The analysis of genotypic and phenotypic parameters showed that there was low influence of the environmental factors on the performances of the accessions. Conclusions applications of findings : There was a the low difference between the phenotypic and genotypic variances for all characters. High broad sense heritability estimates recorded for all characters and the expected genetic advance were variables. The high expected genetic advance observed in the vegetative characters are better in the yield characters. The results from this study provide useful information in selection of parents that breeders could exploit in sorghum improvement program in Cameroon.