We investigate temporal variations of the solar neutrino flux in 1970-1997 .
The periods of 11 , 5 and 2 years have been found in the variations of the neutrino flux .
The results indicate that a periodicity close to 5 years is the most significant in the data from both the Homestake and GALLEX experiments .
Two groups of the solar activity indices have been distinguished regarding their interconnection with the neutrino flux series .
The first group contains the indices showing predominantly 11-year period , while a periodicity at approximately 5 years is observed in the second group .
The correlation coefficients between the neutrino flux and indices from the first group are negative , with their module not exceeding 0.5 .
The second group is characterized by positive correlation with the neutrino counting rates with coefficients not lower than 0.6 .
A discussion of findings is presented .