This study was conducted to the Histomorphological Study of subacute Oral Administration of Codeine on Testis of Adult Albino Wistar Rats. The objectives of the study include; to investigate the effects of codeine on the histology of the seminiferous tubules, interstitial cells of Lydig of the testis in adult albino Wistar rats at light microscopic level, to assess sperm count and motility following codeine administration in adult albino rats, to evaluate the effects of codeine on body and organ (testis) weight ratio in adult albino rats and to find out the effect of codeine on sperm morphology and sperm motility. Data obtained were subjected and calculated for one-way analysis of variance (ANOVA), followed by student t-test. The results were expressed as mean ± standard error of mean. Analyses of data were carried out using computer statistical software package SPSS version 20. All statement of differences was based on significance at p<0.05. Twenty male albino rats were used. The animals were divided into 4 groups of 5 rats each, Groups 1, II, III and IV. Group I serve as the control group and were given normal feed and water ad libitum for 28 days. Group II rats were administered codeine 30mg/kg by orogastric intubation daily for 28 days in addition to normal feed and water ad libitum. Group III rats were administered codeine 60mg/kg. Group IV rats were administered codeine 90mg/kg. Ethical clearance was obtained from the animal ethical committee, Bayero University Kano for the study.Results from this study showed that There was a significant decrease in mean of initial - final body weights of the animals. Sperm count decreases significantly as doses increases, there was a significant decreased in normal sperm cell morphology as doses increases. sperm cell motility showed significant decreases as doses increases. Result of histopathology of the testis showed; mild focal seminiferous tubular hypertrophy, tubules becoming star shaped, mild focal oedema which is also seen in blood vessels, scanty interstitial connective tissue, increased inter tubular space, mild focal degeneration and disruption of seminiferous tubules, disruption and crumbling of the cell of the spermatogenic series.