The objective of the given research is to study changes in crossing over frequency and state of main components of fitness at linear flies D. Melanogaster in dependence on age and experimentally created modifications in the genotype. Research techniques are traditional and well applied in genetics methods of revealing main components of fitness D. melanogaster in particular fertility, survival in extreme conditions (high temperature exposure and starvation), life expectancy etc., are used. Beside before mentioned physiological components of fitness genetic (defining crossing over frequency) and genetic biochemical (defining functional state of gene-enzymatic system Adh) characteristics of fitness are also applied. Crossing over frequency, activity and thermal resistance have been defined with the help of common methods. Being guided and published in special literature data we have used these characteristics to evaluate viability and general fitness of D. melanogaster. Reliability of the obtained data has been evaluated according to student criterion (p<0.05). The analysis result prove that fertility differs in mutants according to the age except the wild type which has more ability in fertility and unchangeable with age and all the mutants lines of Drosophila melanogaster (b, cn, cn and vg) have more fertility than the others. The data of showed that the mutant liens of Drosophila maelanogaster (b, cn, cn and vg) have more fertility than the other mutants. This fact should be taken into consideration while creating new genotypes through outbreeding, genetic engineering and while developing genetic theories of maturation and aging.