This thesis deals with the analysis of the distribution
of galaxies and clusters, describing some observational problems and
statistical results.
First chapter gives a theoretical introduction, aiming to describe
the framework of the formation of structures, tracing the history
of the Universe from the Planck time,
sec and temperature corresponding to 
GeV,
to the present epoch.
The most usual statistical tools and models of the galaxy
distribution, with their advantages and
limitations, are described in chapter two.
A study of the main observed properties of galaxy clustering,
together with a detailed statistical analysis of the effects of selecting
galaxies according to apparent magnitude or diameter, is reported in
chapter three. Chapter four delineates some properties of groups
of galaxies, explaining the reasons of discrepant results on
group distributions.
Chapter five is a study of the distribution of galaxy clusters, with different statistical tools, like correlations, percolation, void probability function and counts in cells; it is found the same scaling-invariant behaviour of galaxies. Chapter six describes our finding that rich galaxy clusters too belong to the fundamental plane of elliptical galaxies, and gives a discussion of its possible implications. Finally chapter seven reviews the possibilities offered by multi-slit and multi-fibre spectrographs, and I present some observational work on nearby and distant galaxy clusters. In particular, I show the opportunities offered by ongoing surveys of galaxies coupled with multi-objet fibre spectrographs, focusing on the ESO Key Programme A galaxy redshift survey in the south galactic pole region to which I collaborate and on MEFOS, a multifibre instrument with automatic positioning. Published papers related to the work described in this thesis are reported in the last appendix.