We determined the effects of 16 wk of storage at low temperature (4 C) in darkness on the viability, growth, photosynthetic parameters, and biochemical composition of four diatom cultures. Significant differences in cell density and proximal composition were observed for all diatoms throughout storage. Cell density increased with time of storage for all diatoms. Protein content increased for Navicula incerta, Nitzschia laevis, and Navicula sp., whereas lipid content increased during storage in only N. incerta. When the stored diatoms were used as inocula in fresh medium, they increased their viability, generating a lag phase for Nitzschia thermalis var. minor, N. incerta, and Navicula sp. cultures. There were noted species-specific modifications in proximal composition, ash-free dry weight, and photosynthetic parameters in response to storage. We conclude that N. thermalis, N. incerta, N. laevis, and Navicula sp. can be stored at 4 C for 16 wk and are viable in new cultures.