[en] Mutagenic action of gamma-ray from ¹³⁷Cs on rice variety Guang Lu dwarf 4 was investigated. It was indicated that the chlorophyll mutation of rice plant induced by ¹³⁷Cs was similar to that by ⁶⁰Co. The maximum frequency of M₁ segregating plant and M₂ chlorophyll deficient seeding were observed at the 35 KR radiation dosage and at the 50 R/m radiation dose rate of both radiation sources. Meanwhile, similar chlorophyll mutation spectrum, which included the types of abbina, xantha, striata, tigrina and viridis for both ¹³⁷Cs and ⁶⁰Co was found. The maximum frequences were the type of albina mutation in the spectrum