Background: Exposure to ionizing radiation is known to have various effects on hematological parameters of biological sample. This study was aimed at evaluating the effect of ionizing radiation on some hematological parameters in guinea pigs. Materials and Methods: Thirty-six (36) apparently healthy adult guinea pigs of both sexes weighing between 700g – 1200g were used in the present study. The guinea pigs were categorized into three groups, 12 per group; group A (control), group B, and C were exposed to X-rays within the diagnostic range, using 70 kV and 12.5mAs; using X-ray machine MS-185, serial no. 0904 GE at a source to skin distance (SSD) of 90cm. Blood samples were collected from all the guinea pigs at intervals of 1 hour, 24 hours 72 hours, 168 hours and 336 hours post-irradiation, and subjected to standard hematological analysis.  Results: A continuous decline in the mean total white blood cell count and mean lymphocyte, monocyte, neutrophil and eosinophil count after 1hour in both groups was observed, and more pronounced after 24 hours post-irradiation. However, stability was observed 72 hours post-irradiation in both groups. Conclusion: This study found a depleting effect of low dose ionizing radiation on white blood cell count, with appreciable recovery occurring after 72 hours onward.