A class of unbiased ratio-type estimators in two (double) phases sampling has been constructed. It has been shown that Sukhatme's (1962) estimator is a particular member of the proposed class. Variance expression of the proposed class has been derived and optimum estimator in the class is identified. An empirical study is carried out to illustrate the performances of constructed estimator over various other estimators. Further, the cost aspect has also been considered.